The removal of dust and other particles from brake drum assemblies is necessary in order to prevent wear and tear on the drums and linings, and as a safety measure. Ordinarily, in such a cleaning operation the wheel and the outer cover of the drum assembly are removed and a stream of air under pressure from a hose is directed against the various parts of the brake assembly to force dust and other particles therefrom. The dust contains ground-up brake lining material which is extremely high in asbestos. When such material is blown into the air from the brake assemblies, a substantial degree of air pollution occurs within the working area. Thus not only the mechanics working on the brakes but also anyone within, for example, fifty feet of the operator is subjected to breathing air that is contaminated with finely divided asbestos material. Furthermore the material which blown into the air clings to and coats almost anything in the working area such as light fixtures, water pipes, furniture, shelves, other vehicles, and floors, resulting in an expensive cleanup operation. In my initial efforts to solve the problem I first attempted to encase the entire brake assembly in a canvas bag and hook it up to a vacuum cleaner. Realizing that such bag structure would collapse under vacuum and be of no practical value I conceived of a device in the form of a bonnet formed of a durable plastic or light aluminum that would not collapse under vacuum, and subsequently tested and reduced to practice the device of the present invention.
I am aware that many efforts to minimize dust removal problems such as I have described above, involving various kinds of, apparatus and equipment for, that purpose, have been suggested, as for example the devices disclosed in U.S. Pat. Nos. 3,510,905 and 3,731,340. None of these to my knowledge are in commercial use. I believe that is due in part, to the fact that such devices are either expensive, hard to maintain, or not adaptable for use with the variety of brake drum assemblies that are encountered in every day operations in a repair shop.